Influence of thermal manipulations on quail embryo during embryogenesis and post hatching

Abstract

The artificial incubation temperature is constant throughout the incubation period however the natural incubation temperature fluctuates widely. Thermal manipulation means increasing or decreasing the incubation temperature at a critical period, certain temperature and certain duration. Quail embryo intermittent thermal manipulation is an effective and safe protocol which lead to growth enhancement and increased muscle yield at slaughter age in association with several alterations in molecular, physiological and biochemical parameters. Muscle histogenesis and development starts early in embryonic life through early post hatch. TM have an immediate and long-term effects on myoblast proliferation and differentiation. The current study aimed to shed the light on the onset and long-term effects of intermittent thermal manipulations during two-time window, early / late, of embryogenesis in Japanese quail (Coturnix japonica) on embryonic development, hatchability, muscle histogenesis and post hatching growth performance. The eggs of control group (Ctrl) was incubated at 37.7°C and 55% RH for 17 days. Three thermally treated groups were incubated intermittently at 41°C and 65% RH intermittently (3 hours / day): Group (EE) during early embryogenesis (ED6 – ED8), group (LE) during late embryogenesis (ED12 – ED14), and group (EL) was thermally treated in both time window (early and late). The hatched chicks were reared under optimal managemental conditions (3 replicates per treatment). The results revealed that early embryonic TM lead to a significant hypertrophy of quail breast muscle at post hatch day 35 without any deleterious effects on embryonic development and growth, embryo yolk consumption and hatchability. Intermittent short-term (3h) thermal manipulation(41°C) protocols during early embryogenesis (ED6 – ED8) could be recommended to enhance muscle mass growth and breast muscle yield in quail broilers instead of the constant incubation temperature used in commercial hatcheries.